Fuel injectors for gas turbine engine combustion chambers are currently manufactured using conventional manufacturing techniques to produce swirler vanes and swirler vane passages between the swirler vanes. Fuel injectors for gas turbine engine combustion chambers are currently manufactured by casting, machining from solid or electro-discharge machining from solid. The conventional manufacturing techniques limit the complexity of the shape of the swirler vanes and incur significant non-recurring costs each time the configuration of the swirler vanes is changed.
The direct laser deposition (DLD) manufacturing technique may offer significant advantages in that the configuration of the swirler vanes may be much more complex and the non-recurring costs of changing the configuration of the swirler vanes in minimal.
Direct laser deposition (DLD), alternatively known as selective laser sintering (SLS) or selective laser melting (SLM), is an additive manufacturing technique by which metallic parts are produced by fusing metallic powder particles together with a relatively low-power laser beam or other suitable radiation beam or energy beam. Direct laser deposition uses a computer aided design (CAD) model of a component, or article, and the CAD model of the component, or article, is divided into a plurality of layers. Layers of powder metal are sequentially placed on a powder bed apparatus and the radiation beam is moved in a predetermined pattern over the each layer of powder in turn to build up the component, or article, layer by layer.
However, it is difficult and expensive to manufacture fuel injectors for gas turbine engine combustion chambers using direct laser deposition because the configuration of the swirler vanes is such that the swirler vanes have over-hanging and/or re-entrant features. Currently the direct laser deposition process is limited to a maximum over-hang angle of about 30° relative to a horizontal plane and the direct laser deposition process builds up components or articles vertically. Over-hang angles less than this produce significant distortion of the component or article because the next layer of powder deposited is not sufficiently supported.
The over-hanging and/or re-entrant features require additional slave structures to be provided on the component, or article, to prevent distortion or loss of form, or shape, during the direct laser deposition manufacturing process. In addition these additional slave features have to be removed, e.g. machined, from the finished component, or article, adding cost and introducing a possibility of introducing defects in the component, or article, due to the machining process. The additional slave features form a scaffold structure that is modelled into the component, typically by modifying the computer aided design (CAD) model of the component using the direct laser deposition (DLD) software prior to start of the manufacturing process. The form of the additional slave features, or scaffold structure, is dependent on how the component is orientated relative to the horizontal plane of the powder bed apparatus. For example if the component is orientated such it is does not have any over-hanging, or un-supported, features, then no additional slave features are required.
Therefore the present invention seeks to provide a novel fuel injector which reduces or overcomes the above mentioned problem.
The present invention seeks to provide a novel method of manufacturing a fuel injector which reduces or overcomes the above mentioned problem.